Infrared transmission chalcogenide glasses

ABSTRACT

A glass composition and a method for producing the glass composition having an improved infrared transmission are provided. The composition includes indium and or cadmium; germanium; phosphorus, arsenic, and/or antimony; silver; lead; and sulfur, selenium, and/or tellurium. The method is performed by melting a mixture for a time period of between about 5 to about 48 hours and mixing the mixture at a temperature range that is between about 600-1000° C.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/181,774, filed Jun. 14, 2016, that claims the benefit of U.S.Provisional Application Ser. No. 62/180,904, filed Jun. 17, 2015, theentire contents of which are all incorporated by reference herein.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates to a glass composition, and a method forproducing the glass composition, having an improved infraredtransmission. More particularly, the present disclosure relates toimproved infrared transmitting chalcogenide glasses having indium and/orcadmium.

2. Field of the Related Art

A chalcogenide is a chemical compound having at least one chalcogenanion and one more electropositive element. Chalcogens include chemicalelements in group 16 of the periodic table, the oxygen family, butexcluding oxygen itself. Chalcogenide glasses contain chalcogens,generally sulfides, selenides, and tellurides. Many chalcogenide glassesare sulfur-based with arsenic-sulfur (As—S) or germanium-sulfur (Ge—S)bonds. Applications for chalcogenide glasses typically involve the 8-14μm wavelength range. It is generally observed that ppm levels of oxygencontamination cause reduced transmission. It is believed that thisreduced transmission is due to the absorption of light bygermanium-oxygen (Ge—O) or arsenic-oxygen (As—O) bonds that form duringthe melting process for formation of the glass. This, in turn, leads toreduced performance for optical properties or systems that have thisglass.

To improve transmission, glass is often processed by distillation withor without the presence of reactive chemicals, such as Al, Mg, AlCl₃ orTeCl₄. However, the transmission improvement is usually slight. Also,significant cost increases are associated with the complex processingrequired by this distillation process. Alternately, the glass can beprepared from exceptionally pure raw materials, however this will add tothe cost of the batch. Also, these raw materials can be difficult tosource, as well as handle in manner that does not introduce oxygen.

Also, improved IR transmission is important for applications involvingthermal imaging, spectroscopy, and CO₂ laser transmission, to name afew. In order to achieve sufficient transmission, soft hygroscopic andtoxic crystalline materials are often used. However, such materials arealso limited in terms of fabrication methods that can be used, namelyfiber drawing and lens molding.

FIG. 1 shows the prior art arsenic-selenium (As—Se) glass. In this priorart glass, there occurs arsenic-oxygen (As—O) bonds with absorption near14 μm. The presence of germanium (Ge) in germanium-arsenic-selenium(Ge—As—Se) glass or germanium-antimony-selenium (Ge—Sb—Se) glass resultsin germanium-oxygen (Ge—O) bonds and absorption (i.e., a drop intransmittance) near 12.5 μm. The difference in wavelengths for theseabsorption features, shown in FIG. 1, is due to the frequency of thebond vibration that is a function of bond strength divided by the atomicmass of the atoms. Thus, a metal with lower bond energy and with oxygenor higher atomic mass will result in a lower frequency vibration andlonger wavelengths for the absorption.

Thus, there is a need to increase the transmission of typical glass inorder to address new applications that are not otherwise suitable fortraditional glass or crystals.

BRIEF SUMMARY OF THE PRESENT DISCLOSURE

The present disclosure provides a chalcogenide glass having improvedinfrared transmission.

The present disclosure also provides such chalcogenide glass for use inglasses in the long wavelength infrared range of 8 μm to 15 μm overcommercially available glasses.

The present disclosure further provides such chalcogenide glasses thathave indium (In), cadmium (Cd), or a combination of both.

The present disclosure yet further provides such chalcogenide glassesthat can be sulfur (S), selenium (Se), or tellurium (Te) based.

The present disclosure still further provides a method for producingsuch chalcogenide glass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of comparing transmission percentage of variouscommercial (prior art) glasses at a given wavelength.

FIG. 2 is a plot of comparing transmission percentage at a givenwavelength for germanium-galium-selenium (Ge—Ga—Se) andgermanium-indium-selenium (Ge—In—Se).

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides for glass for use in glasses that havean improved transmission in the long wavelength infrared (IR) range.Further, the improved transmission is in the 8 μm to 15 μm range overpresent, commercially available glasses.

The glasses of the present disclosure are chalcogenide glasses. Thus,the present glasses have chemical elements in group 16 of the periodictable. Although Oxygen is in group 16, oxygen itself is not achalcogenide. These chalcogenide glasses also have cadmium, indium, or acombination thereof, to increase transmission. The chalcogenide glassesof the present disclosure can be sulfur (S), selenium (Se), or tellurium(Te) based.

For elements of interest in forming chalcogenide glasses, such aslate-transition and post-transition metals (d¹⁰ ions) and metalloids,the electronegativity tends to increase with atomic mass. Of theseelements, only indium and cadmium possess the ability to form a largepart of a chalcogenide glass combined with high atomic mass and lowelectronegativity. The addition of these two elements to a chalcogenideglass leads to the preferential formation of cadmium-oxygen (Cd—O) orindium-oxygen (In—O) bonds over germanium-oxygen (Ge—O) that havefrequencies in the 250-300 cm⁻¹ range that correspond to wavelengths of30-40 μm. Alkaline, alkaline-earth and rare-earth elements have lowelectronegativity and can have high mass. However, these elements areionic, have low solubility, and do not act to preferentially bind oxygen(O). The addition of these elements into sulfide, selenide and tellurideglass results in the removal of oxide impurity absorption bands andrestoration of the fundamental glass transmission range, typically 12 μmfor sulfide, 16 μm for selenide, and 20 μm for telluride glass.

The addition of indium (In), cadmium (Cd), or both, to the glassincreases significantly the transmission of the glass. While not beingbound by any theory, it is believed that the improved transmissionarises from the combination of low electronegativity and high atomicmass indium (In), cadmium (Cd). It is further believed that the oxygen(O) will preferably bond to elements of the glass having lowestelectronegativity, i.e the Cd In which also gives the highest possiblemetal-oxygen bond strength.

In a first embodiment, the chalcogenide glass has no cadmium (Cd). Inthis embodiment, the amount of indium (In) is between about 2% to about20%, and more preferably, between about 5% to about 15%, of the totalweight of the glass.

In a second embodiment, the chalcogenide glass has no indium (In). Inthis embodiment, cadmium (Cd) is present in an amount between about 0.5%to about 10% and, more preferably, between about 2% to about 5%.

In a third embodiment in which the chalcogenide glass has cadmium (Cd)and indium (In), the amount of cadmium (Cd) is between about 0.5% andabout 10% and the amount of indium (In) is between about 5% and about10%. More preferably, the amount of cadmium (Cd) is between about 2% andabout 5% and the amount of indium (In) is between about 5% and about10%.

In each of these three embodiments set forth above, the remainder of thecomposition is between about 10% to about 30% germanium (Ge); betweenabout 2% to about 40% of phosphorus (P), arsenic (As) and/or antimony(Sb); 0% to about 10% lead (Pb); 0% to about 20% silver (Ag); and about30% to about 80% of one or more of the chalogens, sulfur (S), selenium(Se) and/or tellurium (Te).

In each of the three embodiments described above, the remainder of thecomposition is alternatively comprised of at least about 5% of germanium(Ge) and at least about 1% of (P), arsenic (As) or antimony (Sb). Theseelements prevent the formation of crystals from the melt during coolingin the glass formation process.

Optionally, in each of the three embodiments, each composition can havebetween about 7% to about 25% of a halide. The halide can include, butnot be limited to, chlorine (CI), bromine (Br), or iodine (I).

As a further option, each of the three embodiments can have betweenabout 5% to about 20% of an alkali. The alkali can include, but not belimited to, potassium (K), rubidium (Rb), or cesium (Cs).

In addition to the three embodiments discussed above, the presentdisclosure further provides other embodiments. For example, in two otherembodiments, namely fourth and fifth embodiments, each embodiment hasindium (In). Generally, indium (In) is preferable in glass compositions(and methods of making same) as compared to cadmium (Cd), since indium(In) has lower toxicity, higher glass stability, and a wider array ofcompositions in which it can be used.

The fourth embodiment is a gallium sulfide (Ga₂S₃) lanthium sulfide(La₂S₃) based chalcogenide glass composition. The fifth embodiment is agallium selenide (GaSe) lanthium selenide (LaSe) based chalcogenideglass composition. In each of these embodiments, the gallium (Ga)increases the solubility of ionic species, such as alkaline andrare-earth elements, in chalcogenide glass.

In these fourth and fifth embodiments, indium (In) can be substitutedfor gallium (Ga) to improve infrared transmission however there is somereduction of the ionic solubility. For example, indium (In) can besubstituted for up to 50% for arsenic (As), antimony (Sb) or gallium(Ga) in sulfide based glass. Indium (In) can also be substituted up to100% for arsenic (As), antimony (Sb) or gallium (Ga) in selenide basedglass. This latter substitution and effect is not possible with cadmium(Cd).

The fourth embodiment provides a gallium sulfide (Ga₂S₃) lanthiumsulfide (La₂S₃) based chalcogenide glass composition. In this fourthembodiment, indium (In) is present between about 0.1% to about 50%,gallium sulfide (Ga₂S₃) is present between about 20% to about 80%, andlanthium sulfide (La₂S₃) is present between about 15% to about 35%. Inthis fourth embodiment, the combination of gallium sulfide (Ga₂S₃) andindium (In) does not exceed 80% of the total composition.

The fifth embodiment of gallium selenide (GaSe) lanthium selenide (LaSe)based chalcogenide glass composition, indium (In) is present betweenabout 0.1% to about 80% and lanthium selenide (LaSe) is present betweenabout 15% to about 35%. In this fifth embodiment, gallium selenide(GaSe) is optional because up to 100% of the gallium (Ga) can besubstituted with indium (In). However, gallium selenide (GaSe) can bepresent in an amount up to about 80%, with the remainder being indium(In), such that the combination of gallium selenide (GaSe) and indium(In) does not exceed about 80% of the composition.

Examples 1 through 8 below are compositions according to the firstembodiment, in which indium (In) is present, but there is no cadmium(Cd). These Examples encompass the first, third, fourth and fifthembodiments, but not the second embodiment.

Example 1

Composition Percent (%) Total Weight of Glass indium (In) between about2-20% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or Betweenabout 50-80%. tellurium (Te)

Example 2

Composition Percent (%) Total Weight of Glass indium (In) between about5-15% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 50-80% tellurium (Te)

Example 3

Composition Percent (%) Total Weight of Glass indium (In) between about2-20% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Example 4

Composition Percent (%) Total Weight of Glass indium (In) between about5-15% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Example 5

Composition Percent (%) Total Weight of Glass indium (In) between about2-20% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 50-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs)

Example 6

Composition Percent (%) Total Weight of Glass indium (In) between about5-15% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 50-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs)

Example 7

Composition Percent (%) Total Weight of Glass indium (In) between about2-20% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Example 8

Composition Percent (%) Total Weight of Glass indium (In) between about5-15% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Examples 9 through 16 below are compositions according to the secondembodiment, in which there is cadmium (Cd), but no indium (In).

Example 9

Percent (%) Total Weight of Glass cadmium (Cd) between about 0.5-10%germanium (Ge) between about 10-30% phosphorus (P), arsenic (As), and/orbetween about 2-40% antimony (Sb) silver (Ag) at most about 20% lead(Pb) at most about 10% sulfur (S), selenium (Se), and/or between about50-80% tellurium (Te)

Example 10

Percent (%) Total Weight of Glass cadmium (Cd) between about 2-5%germanium (Ge) between about 10-30% phosphorus (P), arsenic (As), and/orbetween about 2-40% antimony (Sb) silver (Ag) at most about 20% lead(Pb) at most about 10% sulfur (S), selenium (Se), and/or between about50-80% tellurium (Te)

Example 11

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% germanium (Ge) between about 10-30% phosphorus (P), arsenic(As), and/or between about 2-40% antimony (Sb) silver (Ag) at most about20% lead (Pb) at most about 10% sulfur (S), selenium (Se), and/orbetween about 30-80% tellurium (Te) chlorine (Cl), bromine (Br), and/orbetween about 7-25% iodine (I)

Example 12

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Example 13

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% germanium (Ge) between about 10-30% phosphorus (P), arsenic(As), and/or between about 2-40% antimony (Sb) silver (Ag) at most about20% lead (Pb) at most about 10% sulfur (S), selenium (Se), and/orbetween about 50-80% tellurium (Te) potassium (K), rubidium (Rb), orbetween about 5-20% cesium (Cs)

Example 14

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 50-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs)

Example 15

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% germanium (Ge) between about 10-30% phosphorus (P), arsenic(As), and/or between about 2-40% antimony (Sb) silver (Ag) at most about20% lead (Pb) at most about 10% sulfur (S), selenium (Se), and/orbetween about 30-80% tellurium (Te) potassium (K), rubidium (Rb), orbetween about 5-20% cesium (Cs) chlorine (Cl), bromine (Br), and/orbetween about 7-25% iodine (I)

Example 16

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% germanium (Ge) between about 10-30% phosphorus (P), arsenic (As),and/or between about 2-40% antimony (Sb) silver (Ag) at most about 20%lead (Pb) at most about 10% sulfur (S), selenium (Se), and/or betweenabout 30-80% tellurium (Te) potassium (K), rubidium (Rb), or betweenabout 5-20% cesium (Cs) chlorine (Cl), bromine (Br), and/or betweenabout 7-25% iodine (I)

Examples 17 through 32 below are compositions according to the thirdembodiment, in which there is both indium n) and cadmium (Cd).

Example 17

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 2-20% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 50-80% tellurium (Te)

Example 18

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 5-15% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 50-80% tellurium (Te)

Example 19

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 2-20% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 30-80% tellurium (Te) chlorine (Cl),bromine (Br), and/or between about 7-25% iodine (I)

Example 20

Composition Percent (%)Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 5-15% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 30-80% tellurium (Te) chlorine (Cl),bromine (Br), and/or between about 7-25% iodine (I)

Example 21

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 2-20% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 50-80% tellurium (Te) potassium (K),rubidium (Rb), or between about 5-20% cesium (Cs)

Example 22

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 5-15% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 50-80% tellurium (Te) potassium (K),rubidium (Rb), or between about 5-20% cesium (Cs)

Example 23

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 2-20% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 30-80% tellurium (Te) potassium (K),rubidium (Rb), or between about 5-20% cesium (Cs) chlorine (Cl), bromine(Br), and/or between about 7-25% iodine (I)

Example 24

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about2-5% indium (In) between about 5-15% germanium (Ge) between about 10-30%phosphorus (P), arsenic (As), and/or between about 2-40% antimony (Sb)silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur (S),selenium (Se), and/or between about 30-80% tellurium (Te) potassium (K),rubidium (Rb), or between about 5-20% cesium (Cs) chlorine (Cl), bromine(Br), and/or between about 7-25% iodine (I)

Example 25

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 2-20% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 50-80% tellurium (Te)

Example 26

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 5-15% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 50-80% tellurium (Te)

Example 27

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 2-20% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 30-80% tellurium (Te) chlorine(Cl), bromine (Br), and/or between about 7-25% iodine (I)

Example 28

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 5-15% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 30-80% tellurium (Te) chlorine(Cl), bromine (Br), and/or between about 7-25% iodine (I)

Example 29

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 2-20% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 50-80% tellurium (Te) potassium(K), rubidium (Rb), or between about 5-20% cesium (Cs)

Example 30

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 5-15% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 50-80% tellurium (Te) potassium(K), rubidium (Rb), or between about 5-20% cesium (Cs)

Example 31

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 2-20% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 30-80% tellurium (Te) potassium(K), rubidium (Rb), or between about 5-20% cesium (Cs) chlorine (Cl),bromine (Br), and/or between about 7-25% iodine (I)

Example 32

Composition Percent (%) Total Weight of Glass cadmium (Cd) between about0.5-10% indium (In) between about 5-15% germanium (Ge) between about10-30% phosphorus (P), arsenic (As), and/or between about 2-40% antimony(Sb) silver (Ag) at most about 20% lead (Pb) at most about 10% sulfur(S), selenium (Se), and/or between about 30-80% tellurium (Te) potassium(K), rubidium (Rb), or between about 5-20% cesium (Cs) chlorine (Cl),bromine (Br), and/or between about 7-25% iodine (I)

The glass, and glasses formed therefrom, of the present disclosure arepreferably prepared by melting a mixture of the raw elements or binaryhalide and/or chalcogenide compounds for a period of from 5 to 48 hours,preferably from 10 to 20 hours. The glass can be melted in a sealedcontainer, such as a fused quartz ampoule, or in an open crucible, undercontrolled atmosphere and the liquid glass melt can be mixed via rockingor stirring. The mixing occurs in a temperature range of 600° C. to1000° C., preferably in the temperature range of 850° C. to 1000° C.

Without being bound by a particular theory, it is believed that in thetemperature range of 700° C. to 1000° C., the oxygen (O) atoms areeffectively transferred from germanium-oxygen (Ge—O) to indium-oxygen(In—O) and/or cadmium-oxygen (Cd—O) bonds. Less indium (In) or cadmium(Cd) are needed to achieve comparable optical properties when melted athigher temperatures than the same composition melted at lowertemperatures. Thus, by melting at higher temperatures in the rangesaccording to the present disclosure, the indium (In) content can bereduced to as low as 2% while still achieving effective removal ofoxygen (O) impurities.

It is also believed that there is also a kinetic component to theimpurity removal process. Thus, at least six (6) hours is needed whenthe indium (In) content is 10%. It appears that there is an increasedefficiency when a lower indium (In) content is present if the melt timeis longer than twelve (12) hours.

Using long or longer melt times as a method for remediation oftransmission of indium-free compositions results in the absence of asignificantly altered refractive index or other adverse effects on thecomposition properties. This is particularly useful for compositionsthat do not have germanium (Ge), as the solubility for indium (In) inthe glass is low, causing crystal formation.

Under such longer processing, notwithstanding the above discussedcompositions and ranges, it is also possible to use indium (In) as adopant if the indium (In) is in an amount under about 2%, morepreferably, under about 1%. In such an embodiment, the impact oninfrared transmission can be significant, but less in magnitude than theembodiments having more than about 2% indium (In).

Referring to FIG. 2, there is shown a graph of the percent transmissionon the vertical axis and wavelength on the horizontal axis forGe₂₀In₁₀Se₇₀ that has been melted at different temperatures and times.The red line, reference numeral 30, is 950° C. for 4 hours, the blueline, reference numeral 32, is 950° C. for 12 hours and the black line,reference numeral 34, is 800° C. This graph shows that, in addition toindium (In), a longer time at a higher temperature is necessary to fullybind oxygen.

Applications for the glasses of the present disclosure include, but arenot limited to, thermal imaging, night vision systems, motion controlsystems, spectroscopy, CO2 laser transmission, optical sensor systemsbased on thin films, and infrared transmitting optical fibers.

As used in this application, the word “about” for dimensions, weights,amounts, and other measures means a range that is ±10% of the statedvalue, more preferably ±5% of the stated value, and most preferably ±1%of the stated value, including all subranges therebetween.

It should be noted that where a numerical range is provided herein,unless otherwise explicitly stated, the range is intended to include anyand all numerical ranges or points within the provided numerical rangeand including the endpoints. Thus, the word “between” is intended toinclude endpoints.

It should also be noted that the terms first, second, third, and thelike may be used herein to modify various elements. These modifiers donot imply a sequential or hierarchical order to the modified elementsunless specifically stated.

Although described herein with reference to one or more exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes can be made and equivalents can be substituted forelements thereof without departing from the scope of the presentdisclosure. In addition, many modifications can be made to adapt aparticular situation, construction, operation, or material to theteachings of the disclosure without departing from the scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment(s) disclosed as the best mode contemplated,but that the disclosure will include all embodiments falling within thespirit and scope of the appended claims.

What is claimed is:
 1. A chalcogenide glass composition, the compositionconsisting essentially of, in percent by weight of the total weight ofthe composition: gallium; indium in an amount from about 2% to about20%; germanium; and at least one chalcogen selected from the groupconsisting of: sulfur, selenium, and tellurium, wherein the at least onechalcogen is in an amount from about 30% to about 80%.
 2. Thecomposition of claim 1, wherein the chalcogen is sulfur.
 3. Thecomposition of claim 1, wherein the amount of germanium is from about10% to about 30%.
 4. The composition of claim 1, wherein the at leastone chalcogen is in an amount from about 50% to about 80%.
 5. Thecomposition of claim 1, wherein the composition is prepared by mixing ina temperature range from about 850° C. to 1000° C.
 6. A chalcogenideglass composition, the composition consisting essentially of, in percentby weight of the total weight of the composition: indium; germanium inan amount from about 10% to about 30%; at least one alkali selected fromthe group consisting of: potassium, rubidium, or cesium; at least onechalcogen selected from the group consisting of: sulfur, selenium, andtellurium; and at least one halide selected from the group consistingof: chlorine, bromine, and iodine.
 7. The composition of claim 6,wherein the at least one halide is in an amount from about 7% to about25%.
 8. The composition of claim 6, wherein the at least one halide isbromine.
 9. The composition of claim 6, wherein the chalcogen is sulfur.10. The composition of claim 6, wherein the amount of indium is fromabout 2% to about 20%.
 11. The composition of claim 6, wherein the ateast one chalcogen is in an amount from about 30% to about 80%.
 12. Thecomposition of claim 6, wherein the composition is prepared by mixing ina temperature range from about 850° C. to 1000° C.
 13. The compositionof claim 6, wherein the at east one alkali is in an amount from about 5%to about 20%.
 14. The composition of claim 6, wherein the at east onealkali is cesium.
 15. A chalcogenide glass composition, the compositionconsisting essentially of, in percent by weight of the total weight ofthe composition: indium; germanium; at least one element selected fromthe group consisting of: phosphorus, arsenic, and antimony, wherein theat least one element is in an amount from about 2% to about 40%; and atleast one chalcogen selected from the group consisting of: sulfur,selenium, and tellurium, wherein the at least one chalcogen is in anamount from about 30% to about 80%.
 16. The composition of claim 15,wherein the composition is prepared by mixing in a temperature rangefrom about 850° C. to 1000° C.
 17. The composition of claim 15, whereinthe amount of germanium is from about 10% to about 30%.
 18. Thecomposition of claim 15, wherein the amount of indium is about 2% toabout 20%.
 19. The composition of claim 15, wherein the at least onechalcogen is in an amount from about 50% to about 80%.
 20. Thecomposition of claim 15, wherein the chalcogen is selenium.